Substrate structure, method for forming it, semiconductor lamination structure, method for forming it and method for producing a nitride semiconductor

Abstract

Substrate structure, including: a single crystal substrate heterogeneous to a nitride semiconductor (100) and a crystallized inorganic thin film (130') having several leg parts (130a) configured to contact the substrate (100) such that an integrated cavity (C) is defined between the leg parts (130a) and the substrate (100), and an upper surface (130b) formed continuously so that it extends from the several leg parts (130a) and parallel to the substrate (100), wherein the crystallized inorganic thin film (130') has the same crystal structure as the substrate (100) and wherein the several leg parts (130a) each have a hollow tube shape.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a semiconductor layer made of gallium nitride (GaN) or a mixed nitride of gallium and another metal, and a method for forming the same. The present disclosure also relates to an electronic or optoelectronic device incorporating such a layer, a nitride semiconductor substrate, and a method for producing the same. The technical field of the present disclosure can generally be defined as a substrate structure for forming a high-quality nitride semiconductor layer with a small crystal defect, and a method for forming the same. STATE OF THE ART

[0002] A nitride semiconductor device made of gallium nitride or similar materials typically incorporates an LED. The LED market has grown based on low-power LEDs used for keypads in small household appliances or portable communication devices such as mobile phones, or as backlighting for liquid crystal displays (LCDs). More recently, as the need for a highly efficient, high-power light source for indoor lighting, outdoor lighting, vehicle interior and exterior lighting, and backlighting for large LCDs increases, LEDs are also being developed for high-power products.

[0003] In devices using nitride semiconductors, "heterogeneous" substrates such as sapphire, silicon carbide (SiC), and silicon are most commonly used for growing the nitride semiconductor layer. However, because these heterogeneous substrate materials have mismatched lattice constants and different coefficients of thermal expansion compared to nitrides, the nitride semiconductor layer growing on the heterogeneous substrate contains many crystal defects, such as dislocations. Such defects become a major factor in the degradation of LED performance.

[0004] The sapphire substrate has a higher coefficient of thermal expansion than the nitride semiconductor layer. Therefore, if the nitride semiconductor layer grows at a high temperature and is then cooled, compressive stress is exerted on it. The silicon substrate has a lower coefficient of thermal expansion than the nitride semiconductor layer. Therefore, if the nitride semiconductor layer grows at a high temperature and is then cooled, tensile stress is exerted on it. This causes the substrate to warp, and to prevent warping, it should be very thick. Using a thick substrate only reduces a surface phenomenon but not the stress on the thin film. If the stress on the thin film can be reduced, a thin substrate can be advantageous.Furthermore, the substrate should be ground to a thickness of approximately 100 µm to allow for chip separation after LED fabrication. This configuration, if a thin substrate can be used, would significantly improve LED manufacturing.

[0005] If necessary, the nitride semiconductor layer growing on the heterogeneous substrate should be separated from the substrate. Laser detachment has been proposed as an existing method for this. However, even when using the laser detachment method, the substrate can be bent, and the semiconductor layer can be damaged due to a difference in the coefficient of thermal expansion between the sapphire substrate and the nitride semiconductor. Furthermore, a defect such as a crack in the epitaxial layer can easily be created by laser beam impact, and the epitaxial layer is fragile, resulting in an unstable process. The laser detachment method is accompanied by thermal or mechanical deformation and degradation of the nitride semiconductor. This leads to a loss in the grown thin film and is also energy-inefficient.

[0006] In addition, the biggest problem with LEDs is their low luminous efficacy. Generally, luminous efficacy is determined by the light generation efficiency (internal quantum efficiency), the light emission efficiency (external light extraction efficiency) from a device, and the light amplification efficiency of a phosphor. To increase the performance of an LED, it is important to improve the properties of the active layer with respect to internal quantum efficiency, and it is also important to increase the external light extraction efficiency of the actually generated light.

[0007] A structured sapphire substrate (PSS), produced by forming a structure on a sapphire substrate, is known in the technology to increase the internal quantum efficiency by reducing defects generated during the growth of the nitride semiconductor layer and also to increase the external light extraction efficiency by reducing internal total reflection.

[0008] Fig. Figure 1 is a diagram illustrating a case where a nitride semiconductor layer grows using an existing PSS.

[0009] With reference to Fig. 1(a) A nitride semiconductor layer 20 begins to grow in an existing PSS 10 on the underside of a substrate and grows by epitaxial lateral overgrowth (ELO) such that it covers an upper part of a PSS lens 15. Accordingly, as in Fig. 1(b) shows that a final nitride semiconductor layer 25 with a low dislocation density between displaced regions is obtained.

[0010] If the nitride semiconductor layer consists of GaN, the GaN grows at 1100°C or less. At this temperature, GaN grows due to a growth mode with strong anisotropic properties, as shown in Fig. 1(a) shown, generally only on the underside, and thus the dislocation density decreases in a region where ELO occurs, as in Fig. 1(b) is shown, which improves the crystal quality.

[0011] However, if the nitride semiconductor layer consists of AlN, the effects mentioned above are not achieved. AlN grows at 1300°C or higher, higher than GaN. At this temperature, a growth mode with strongly isotropic properties is used. With reference to Fig. 1(c) Accordingly, AlN 30 grows not only on the underside of the PSS 10, but also actively on a surface of the lens 15. Therefore, the AlN epitaxial layer is very likely to merge before the underside is completely filled, thus creating a gap 40 in the AlN epitaxial layer 35, as shown in Fig. 1(d) is shown. The gap 40 degrades the crystal quality.

[0012] Due to the aforementioned problems, using PSS to grow the AlN epitaxial layer is not straightforward, and consequently, the crystal quality deteriorates. Furthermore, AlN is more susceptible to stress caused by the coefficient of thermal expansion, substrate bending, or similar factors, as the growth temperature of AlN is 100°C or more higher than that of GaN.

[0013] Therefore, a method for separating a substrate with high reliability or a method capable of obtaining a nitride semiconductor, such as a high-quality nitride semiconductor substrate, a nitride semiconductor device, and a nitride semiconductor layer, regardless of the type of material, is required.

[0014] Further state of the art is known from DE 11 2012 002 182 T5 and JP 2002 - 200 599 A. REVELATION Technical Problem

[0015] The present disclosure is designed to solve the problems of related technology, and therefore the present disclosure is designed to provide a substrate structure and a method for forming the same, in which a high-quality nitride semiconductor layer can be formed, wherein a reduced voltage is exerted on the nitride semiconductor layer during the growth of the nitride semiconductor layer and it can also be easily separated from the substrate, and a semiconductor lamination structure that uses the same, and a method for forming the same, and a method for producing a nitride semiconductor using the same. Technical solution

[0016] The problems of the related technology are solved by the subject matter of the pending independent claims.

[0017] In one aspect of the present disclosure, a substrate structure is provided comprising a heterogeneous single-crystal substrate of a nitride semiconductor and a crystallized inorganic thin film with a leg portion configured to contact the substrate to define an integrated cavity between the leg portion and the substrate, and an upper surface extending from the leg portion and parallel to the substrate, wherein the crystallized inorganic thin film has the same crystal structure as the substrate.

[0018] The leg section has a hollow tube shape. Multiple leg sections are provided, and the upper surface is continuous, extending from all of them. The area occupied by the cavity can be larger than the area occupied by the leg sections themselves.

[0019] Another aspect of the present disclosure provides a semiconductor lamination structure which, in addition to the substrate structure configuration, further comprises a nitride semiconductor layer formed on the inorganic thin film. The nitride semiconductor layer can be a film with two or more layers. Although the substrate and the nitride semiconductor layer have different coefficients of thermal expansion, the stress exerted on the nitride semiconductor layer decreases because the integrated cavity can be compressed or stretched by means of the nitride semiconductor layer.

[0020] Another aspect of the present disclosure provides a method for forming a substrate structure, which includes forming a hole-type sacrificial layer structure on a heterogeneous single-crystal substrate of a nitride semiconductor and forming an inorganic thin film on the sacrificial layer structure. The sacrificial layer structure is removed from the substrate on which the inorganic thin film is formed, so that an integrated cavity defined by the substrate and the inorganic thin film is formed. Subsequently, the inorganic thin film is crystallized into the same crystal structure as the substrate.

[0021] Sacrificial layer structuring can be achieved in various ways. After applying a photoresist to the substrate, the sacrificial layer can be formed using a photolithography process. Alternatively, the sacrificial layer can be formed using a nanoprinting process after applying a nanoprinting resin to the substrate.

[0022] The inorganic thin film can be formed within a temperature range where the sacrificial layer structure is not deformed. The inorganic thin film can be formed using ALD (alkali-liquid deposition). Additionally, the sacrificial layer structure can be removed by heat treatment in an oxygen atmosphere or by wet deposition using an organic solvent. The resulting cavity is a space where the sacrificial layer structure has been removed and is therefore absent.

[0023] In the process for forming a substrate lamination structure according to the present disclosure, a nitride semiconductor layer can be formed on the crystallized inorganic thin film using the substrate structure of the present disclosure or after the substrate structure has been formed according to the above-mentioned process.

[0024] In an embodiment for producing a high-quality nitride semiconductor layer or a component or substrate incorporating the same, a nitride semiconductor such as a vertical or horizontal LED, an LED that is transferred or transported to any substrate, or a nitride semiconductor such as a freestanding nitride semiconductor substrate can be produced by separating the substrate and the nitride semiconductor layer in the resulting product of the semiconductor lamination structure fabrication process according to the present disclosure or in the semiconductor lamination structure according to the present disclosure.

[0025] If the substrate structure, the method for its fabrication, and the method for fabricating a nitride semiconductor using it according to the present disclosure are used, it is possible to produce an ultraviolet light detector, an elastic surface wave (SAW) device, an LED, an LD, an electronic microwave device, or the like, which can be extended to modules, systems, or the like that utilize these devices. Furthermore, it is possible to fabricate a freestanding nitride semiconductor substrate. Details of other embodiments are included in the detailed description and the drawings. Beneficial effects

[0026] According to the present disclosure, the substrate structure includes an inorganic thin film defining an integrated cavity, and the inorganic thin film can be contained in such a way that the contact surface with the substrate is minimized. If a nitride semiconductor layer is formed on the substrate structure, the overall stress of the nitride semiconductor layer due to the cavity is reduced. Therefore, the local stress is eased, even though stress is generated at the nitride semiconductor layer due to a difference in the coefficient of thermal expansion between the substrate and the nitride semiconductor layer, and thus the resulting curvature of the substrate can be reduced. Accordingly, it is possible to use a relatively thin substrate even in a large substrate.

[0027] In the semiconductor lamination structure according to the present disclosure, the nitride semiconductor layer is formed on the crystallized inorganic thin film over an integrated cavity. The crystallized inorganic thin film, together with the growing nitride semiconductor layer, can eliminate the strain, thus enabling the nitride semiconductor layer to grow in such a way as to exhibit high quality with a low defect density. Therefore, a high-quality nitride semiconductor layer with a low defect density can be formed, and the internal quantum efficiency can be improved due to the reduction in the nitride semiconductor crystal defect density. Even AlN with a better isotropic growth pattern can be formed with high quality without any irregular gaps.

[0028] In particular, in a method for forming a substrate structure and a semiconductor lamination structure according to the present disclosure, a hole-type sacrificial layer structuring is formed using a controlled method such as photolithography or nanoprinting, so that an integrated cavity is formed not in an irregular or random way, but in a controlled way, thereby ensuring good duplication and excellent device uniformity.

[0029] As a result, a nitride semiconductor epiaxial layer with excellent properties can grow, enabling the implementation of an optoelectronic device with high efficiency and high reliability.

[0030] In particular, the substrate structure and the semiconductor lamination structure, as disclosed herein, incorporate an integrated cavity, thus minimizing contact between the substrate and the nitride semiconductor layer and ensuring a degree of physical separation. Consequently, as the nitride semiconductor layer grows and is subsequently cooled, the nitride semiconductor layer and the substrate can be naturally separated with only a small physical force or impact, without the need to apply significant energy such as that required by a laser. Therefore, the nitride semiconductor layer can be easily separated from the substrate without a laser detachment process, making it possible to fabricate a vertical or horizontal LED, an LED that can be transferred or transported to any substrate, or a freestanding nitride semiconductor substrate, thereby enabling the production of a high-quality nitride semiconductor. DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a diagram illustrating a case where a nitride semiconductor layer grows using an existing PSS. Fig. Figure 2 is a perspective view illustrating each process to demonstrate a substrate structure, a semiconductor lamination structure, a method for forming the same, and a method for producing a nitride semiconductor according to the present disclosure. Fig. Figure 3 is a cross-sectional view along line III-III' of Fig. 2, which represents each process. The Fig. 4 and Fig. Figure 5 are diagrams illustrating various methods for forming a hole-type sacrificial layer structure according to the present disclosure. Fig. Figure 6 is a diagram that better illustrates a crystallized inorganic thin film according to the present disclosure. Fig. Figure 7 is a diagram illustrating that a nitride semiconductor layer and a substrate can be separated with a smaller force according to the present disclosure. BEST EXECUTION METHOD

[0031] Preferred embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. These embodiments are provided for those skilled in the art to obtain a complete understanding of the present disclosure. Therefore, shapes or similar representations of elements in the drawings have been exaggerated for clarity, and identical symbols in the drawings denote identical elements.

[0032] Fig. Figure 2 is a perspective view that illustrates each process for demonstrating a substrate structure, a semiconductor lamination structure, a method for forming the same, and a method for fabricating a nitride semiconductor according to the present disclosure and Fig. Figure 3 is a cross-sectional view along line III-III' of Fig. 2, which represents each process.

[0033] First, as in Fig. 2(a) and Fig. Figure 3(a) shows a hole-type sacrificial layer structure 110 formed on a heterogeneous single-crystal substrate 100 of a nitride semiconductor. The sacrificial layer structure 110 is formed such that it has a hole H. The hole H is an opening that exposes a bottom surface of the substrate 100.

[0034] The victim layer structure 110 can be formed in a variety of ways. Fig. 4 and Fig. Figure 5 are diagrams illustrating various methods for forming a hole-type sacrificial layer structure according to the present disclosure.

[0035] First, the sacrificial layer structure 110 can be formed using a photolithography process. For example, as in Fig. 4(a) shows a photoresist PR applied to the substrate 100. The photoresist PR can be applied to the substrate 100 by any method from the group consisting of rotary coating, dip coating, spray coating, drop coating and potting, of which rotary coating is preferred for the uniformity of the coating film.

[0036] Then, as in Fig. As shown in Figure 4(b), the photoresist PR is exposed (E) using a photomask 112 with a suitable light-shielding pattern 111. Light passing through an area other than the light-shielding pattern 111 exposes part of the photoresist PR, creating an exposed area EA. Subsequently, a photoresist pattern PR' with the hole H may remain if the exposed area EA is developed and removed, as shown in Figure 4(b). Fig. 4(c) is shown here. Although the photoresist PR is a positive, where, for example, the exposed area is removed, a negative photoresist, where the exposed area is not removed, can also be used.

[0037] In this case, experts would understand that the position of the photomask's light-shielding pattern should be changed.

[0038] The light-shielding pattern 111 can be formed by controlling its aperture shape, size, interval, or the like according to a design method of the semiconductor manufacturing process. Similarly, the photoresist pattern PR' can be controlled to have holes with a customized shape, size, and two-dimensional arrangement. This photoresist pattern PR' can be used as the hole-type sacrificial layer structuring 110. If necessary, an additional process, such as a reverse flow process, can be performed to modify the shape of the photoresist pattern PR'.

[0039] In another case, the hole-type sacrificial layer structure 110 can be formed using a nanoprinting process. With reference to Fig. 5(a) A nanoprinting resin R is applied to the substrate 100. The nanoprinting resin R can also be applied to the substrate 100 by any method from the group consisting of rotational coating, dip coating, spray coating, drop coating, and potting, of which rotational coating is preferred for the uniformity of the coating film. A nanoprinting die 114, having a structuring 113 with a suitable non-uniform structure, is prepared. The nanoprinting die 114 can be a master shape produced from silicon or quartz by an ordinary method, or an organic shape produced by duplicating the master shape.

[0040] Then the nanoprinting stamp 114 is applied to the nanoprinting resin R as described in Fig. 5(b) compressed. This fills the nanoprinting resin R between the structurings 113 of the nanoprinting die 114. The nanoprinting resin R is cured by heating combined with compression, exposure to ultraviolet radiation, or exposure to ultraviolet radiation combined with heating. Thereafter, when the nanoprinting die 114 is detached, as in Fig. As shown in 5(c), the hardened nanoprinting resin R' remains on the substrate 100, which can be used as the hole-type sacrificial layer structuring 110.

[0041] To form a hole, the structuring 113 with a non-uniform structure can be formed into a columnar shape by controlling its regular shape, size, interval, or the like according to the design of the nanoprinting process. This allows for the adaptation of the hole shape, size, and two-dimensional arrangement of the hardened nanoprinting resin R' formed from it. If necessary, the shape of the hardened nanoprinting resin R' can also be modified by additional heating or exposure to ultraviolet radiation.

[0042] Furthermore, structuring with a non-uniform pattern can also be achieved using laser contact surface lithography or similar techniques. Laser contact surface lithography utilizes a two- or three-dimensional interference phenomenon obtained through two or more laser sources and is a method for creating a periodic pattern, which can advantageously and easily achieve fine structuring of 1 µm or less.

[0043] According to the above disclosure, the hole-type sacrificial layer structuring 110 can be formed relatively easily with relatively little damage to the substrate and simplified processes compared to an existing PSS method in which the substrate is etched.

[0044] The substrate 100, on which such various hole-type sacrificial layer structures 110 are formed, can employ all possible heterogeneous single-crystal substrates used for heterogeneous epitaxial thin-film growth of a nitride semiconductor layer, such as a sapphire substrate, a silicon substrate, a SiC substrate, a GaAs substrate, or the like. The embodiment is explained based on the sapphire substrate as an example.

[0045] Once the victim layer structure 110 is formed, as in Fig. 2(a) and Fig. As shown in 3(a), an inorganic thin film 130 is formed on the sacrificial layer structure 110, as in Fig. 2(b) and Fig. Figure 3(b) illustrates this. The inorganic thin film 130 subsequently defines an integrated cavity between the inorganic thin film 130 and the substrate 100, and the inorganic thin film 130 can be formed in a temperature range where the sacrificial layer structure 110 is not deformed. The inorganic thin film 130 has a thickness that allows it to stably retain the original shape of the structure after the sacrificial layer structure 110 is removed. The inorganic thin film 130 can be formed by various methods, such as atomic layer deposition (ALD), wet synthesis, metal deposition and oxidation, sputtering, or the like. Furthermore, nitrogen can be supplied in a gaseous or plasma state during the deposition of a metal thin film to form metal nitride.The inorganic thin film 130 can consist of at least one oxide or nitride from the group consisting of silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), zirconium oxide (ZrO2), yttrium oxide (Y2O3)-zirconium oxide, copper oxide (CuO, Cu2O), tantalum oxide (Ta2O5), aluminum nitride (AlN), and silicon nitride (Si3N4). In an embodiment using a sapphire substrate, the inorganic thin film can consist of aluminum oxide. In an embodiment using a silicon substrate, the inorganic thin film can consist of AlN. If the composition and / or the strength and / or the thickness of the inorganic thin film 130 is adjusted, a stress applied to a nitride semiconductor layer formed on the substrate structure using the inorganic thin film 130 can subsequently be controlled.As shown in the figures, the inorganic thin film 130 is formed over the entire substrate 100, so that the sacrificial layer structuring 110 is covered.

[0046] In one embodiment, when the inorganic thin film 130 is formed by ALD, a very thin film with a very uniform thickness can be deposited. Thus, the inorganic thin film 130 coats an inner wall and a bottom surface of the hole H without filling the hole H, and covers an upper surface of the sacrificial layer structuring 110, as can be seen in the cross-sectional view of Fig. Figure 3(b) illustrates this. In this case, a leg portion, representing part of the inorganic thin film and essentially perpendicular to the substrate 100, thus serving as a support structure connecting the substrate 100 and a nitride semiconductor layer formed in a subsequent process, denotes a portion of the inorganic thin film that is accumulated on the inner wall and bottom of the hole H and has a tubular shape. Whether any process other than ALD is used, or even if ALD is used, the hole H can be completely filled with the inorganic thin film 130 if the hole H has a very small diameter. In this case, the leg portion has a columnar shape.

[0047] In general, the hole H can have a diameter of 2 µm or less, so that the upper part of the hole H can be easily filled when the nitride semiconductor layer is formed using ELO. The distance between the holes H can be 2 µm or more. To minimize the density of the leg section, such as a tube or column, it is desirable to maximize the distance.

[0048] In one embodiment, aluminum oxide of a uniform thickness can be formed by a deposition process such as ALD according to the shape of the substrate 100 and the sacrificial layer pattern 110. A wet composition process using a wet chemical can also be used instead of the deposition process. After a wet chemical is uniformly applied according to the shape of the substrate 100 and the hole-type sacrificial layer pattern 110, it can be heated, dried, or chemically reacted to form aluminum oxide. For example, after aluminum precursor powder such as aluminum chloride (AlCl3) is mixed in a solvent such as tetrachloroethylene (C2Cl4), this can be applied to and deposited on the substrate 100, on which the hole-type sacrificial layer pattern 110 is formed, and then heated and reacted in an oxygen atmosphere to form an aluminum thin film.In another case, an oxidation process can be carried out after a metal-aluminum thin film is deposited by sputtering or similar methods to form aluminum oxide. The aluminum oxide is formed in an amorphous state or in a polycrystalline state with fine grains.

[0049] After the inorganic thin film 130 has been formed, the sacrificial layer structuring 110 is selectively removed from the substrate 100, as shown in Fig. 2(c) and Fig. 3(c) is shown. As above with reference to Fig. 4 and Fig. As described in Section 5, the sacrificial layer structuring 110 consists of a polymer such as a photoresist or a nanoprinting resin and can therefore be easily removed by heating. The photoresist, which has a natural ignition point of approximately 600°C, can be easily removed by heating. For easier removal via oxidation, a chemical reaction with oxygen-containing gas can also be added. When a polymer is heated at high temperature in an oxygen atmosphere, the polymer component can be easily removed by a pyrolysis process, commonly called ashing. If heat treatment in an oxygen atmosphere is not available, for example, if the substrate 100 is a silicon substrate that can generate oxides, a wet removal process using an organic solvent can also be employed.

[0050] If the victim layer structuring 110 is removed, as in Fig. 2(c) and Fig. As shown in Figure 3(c), an integrated cavity C can be formed, defined by the substrate 100 and the inorganic thin film 130. The cavity C, defined by the inorganic thin film 130, has an inverse form of the sacrificial layer structure 110. In other words, if the sacrificial layer structure 110 is formed such that it has several spatially separated holes H, the inorganic thin film 130 is connected to the substrate 100 via the multiple holes H. The cavity C represents a part other than the connecting parts between the inorganic thin film 130 and the substrate 100. If, in addition, the holes H are spatially separated from each other by discontinuous spaces, the cavity C is an integrally connected, continuous space.The cavity C has a larger volume when it is an integrated continuous space compared to a case where it is formed with several discontinuous spaces that are spatially separated from each other. In other words, by forming the continuous cavity C, the substrate 100 and a structure formed on it can have a minimal contact area.

[0051] The inorganic thin film 130 in its deposited state is generally amorphous or exhibits polycrystals with fine grains. Heat treatment can be carried out at high temperature, allowing the amorphous or polycrystalline inorganic thin film 130 to be densified and crystallized.

[0052] Although the inorganic thin film 130 and the substrate 100 consist of the same material, for example, the substrate 100 is a sapphire substrate and the inorganic thin film 130 consists of aluminum oxide, or although the inorganic thin film 130 and the substrate 100 consist of different materials, for example, the substrate 100 is a silicon substrate and the inorganic thin film 130 consists of AlN, when the inorganic thin film 130 is heated, for example, to about 1000°C, the inorganic thin film 130 becomes an inorganic thin film 130', which is crystallized by heat treatment into the same crystal structure as the substrate 100, as in Fig. 2(d) and Fig. Figure 3(d) illustrates this. Accordingly, a contact surface (shown with a dashed line in the figures) between the crystallized inorganic thin film 130' and the substrate 100 disappears. This is because the inorganic thin film 130 directly contacts the substrate 100 during the high-temperature heat treatment, causing solid-state epitaxy near the inorganic thin film 130, and thus crystallizing along the crystallization direction of the substrate 100. Solid-state epitaxy begins at a contact surface between the substrate 100 and the inorganic thin film 130, and if the inorganic thin film 130 consists of amorphous material, the crystallized inorganic thin film 130' eventually becomes polycrystalline, or fine polycrystals become larger, or, most preferably, are transformed into single crystals identical to the substrate 100.This crystallization process can be carried out over the entire inorganic thin film 130, and in particular, a portion of the crystallized inorganic thin film 130' above the integrated cavity C acts as an upper surface representing a portion of the inorganic thin film 130' that is substantially parallel to the substrate 100. This surface serves as a support structure connecting the substrate 100 to a nitride semiconductor layer formed in a subsequent process, acting as a nucleation site when the nitride semiconductor epitaxial layer later grows. Thus, it is desirable for the inorganic thin film 130 to be substantially crystallized.

[0053] Fig. Figure 6 is a diagram that better illustrates a crystallized inorganic thin film 130' according to the present disclosure. With reference to Fig. Figure 6 comprises the crystallized inorganic thin film 130', a leg 130a that contacts the substrate 100, and an upper surface 130b that extends from the leg 130a and parallel to the substrate 100. The integrated cavity C is defined by the crystallized inorganic thin film 130' between the crystallized inorganic thin film 130' and the substrate 100. Several leg 130a are provided, and the upper surface 130b is formed continuously, extending from the multiple leg 130a. In one embodiment, the area occupied by the cavity C is larger than the area occupied by the leg 130a.The inorganic thin film 130' is a very important component in the present disclosure, as it defines the integrated cavity C between the inorganic thin film 130' and the substrate 100 and also serves as a seed layer and a support for a nitride semiconductor layer subsequently growing on it.

[0054] As described above, the substrate structure according to the present disclosure includes the substrate 100, the leg part 130a which contacts the substrate 100 to define the integrated cavity C with the substrate 100, and an upper surface 130b which extends from the leg part 130a parallel to the substrate 100, and it also includes the crystallized inorganic thin film 130' which has the same crystal structure as the substrate 100.

[0055] The substrate structure of the present disclosure is defined as a cavity engineering structure (CES) in comparison to an existing PSS. A semiconductor lamination structure utilizing the CES, a method for forming it, and a method for fabricating a nitride semiconductor using it are now described.

[0056] Subsequently, as in Fig. 2(e) and Fig. Figure 3(e) shows a nitride semiconductor layer 150 formed on the crystallized inorganic thin film 130'. The nitride semiconductor layer 150 can be formed into a multilayer structure that includes a suitable buffer layer. The nitride semiconductor layer 150 can consist of any nitride semiconductor material, such as GaN, InN, AlN, or mixtures thereof. x Al y In zN (0 <x, y, z<1). Abhängig von der Art des Materials der Nitridhalbleiterschicht 150 kann eine Bandlücke so angepasst werden, dass ultraviolette Strahlen, sichtbare Strahlen und Infrarotstrahlen emittiert werden. Zu diesem Zeitpunkt wächst die Nitridhalbleiterschicht 150 nicht auf dem Substrat 100. Stattdessen wächst ein Keim auf einem Teil der kristallisierten anorganischen Dünnschicht 130' über dem integrierten Hohlraum C, insbesondere auf der oberen Oberfläche 130b, und die Teile, die mit verschiedenen Wachstumsbedingungen daraus wachsen, werden vereinigt, um schließlich eine Nitridhalbleiterschicht 155 mit einer Dünnschichtform zu bilden, wie in Fig. 2(f) and Fig. Figure 3(f) illustrates this. As described above, in the present disclosure, the nitride semiconductor layer 155 does not grow from the substrate 100, but from the portion of the crystallized inorganic thin film 130' above the integrated cavity C. Thus, the nitride semiconductor layer 155 is formed in a completely different manner than the existing ELO process.

[0057] The growth of crystals in the CES according to the present disclosure can be clearly demonstrated with reference to the Fig. 3(e) and Fig. 3(f) can be understood. Specifically, the nitride semiconductor layer 150 begins to grow on an upper flat surface of the inorganic thin film 130', namely the upper surface 130b, and grows until it covers the leg portion 130a, specifically a hole-shaped upper part. The nitride semiconductor layer 150 growing on the upper surface 130b is connected in a lateral direction, so that the nitride semiconductor layer 155 is formed with a smaller crystal defect.

[0058] In the present disclosure, the crystallized inorganic thin film 130', together with the nitride semiconductor layer 155 growing on it, can eliminate stress and thus play the role of a conformal layer. Since the stress that causes dislocation is also eliminated, the substrate structure can grow with high quality and a lower defect density.

[0059] The stress caused by a physical difference between the substrate and the thin film is converted into elastic energy at the interface to serve as a driving force for dislocation generation. In general, the substrate, due to its greater thickness compared to the thin film, is not easily deformed, and a dislocation is generated in the thin film to relieve the stress. At this point, when the thin film grows beyond a predetermined thickness, a critical thickness, the elastic energy at the interface exceeds the dislocation generation energy, and thus dislocation generation begins.

[0060] However, if the inorganic thin film 130' is thinner than the nitride semiconductor layer 155 in the present disclosure, the critical thickness is much greater, thereby reducing the dislocation generation of the nitride semiconductor layer 155. If the inorganic thin film 130' is sufficiently thinner than the nitride semiconductor layer 155, as described above, it can be considered that its role is replaced by that of the substrate and that the nitride semiconductor layer 155 grows in a state where fewer dislocations are generated. Therefore, it is possible to form the high-quality nitride semiconductor layer 155 with a lower defect density. Since the nitride semiconductor crystal defect density decreases, the internal quantum efficiency can also be improved when the high-quality nitride semiconductor layer 155 is used to fabricate an LED.

[0061] As in Fig. 2(f) and Fig. As shown in Figure 3(f), the semiconductor lamination structure configured as above, according to the present disclosure, comprises the heterogeneous single-crystal substrate 100 of a nitride semiconductor and the crystallized inorganic thin film 130'. The integrated cavity C is defined between the substrate 100 and the inorganic thin film 130'. The substrate structure also includes the nitride semiconductor layer 155, which grows on and is merged with the crystallized inorganic thin film 130' above the integrated cavity C.

[0062] The integrated cavity C is formed in an area where the hole-type sacrificial layer structuring 110 is removed. Since the integrated cavity C is present, if there is a difference in the coefficient of thermal expansion between the substrate 100 and the nitride semiconductor layer 155 formed on it, the integrated cavity C can be stretched or compressed to form a local deformation, thereby dissipating the strain energy. Accordingly, the thermal stress exerted on the nitride semiconductor layer 155 can be reduced, and thus the bending of the substrate 100 can be reduced. Therefore, the substrate 100 can have a relatively small thickness despite its large area.

[0063] In particular, the integrated cavity C can be controlled by adjusting the shape, size, two-dimensional arrangement, or the like of the hole-type sacrificial layer structure. Furthermore, since the hole-type sacrificial layer structure 110 is formed using a controlled process such as photolithography or nanoprinting, the integrated cavity C is not formed irregularly or randomly, but in a controlled manner, thus ensuring good replication and excellent device uniformity.

[0064] As a result, the nitride semiconductor layer 155 with excellent properties can be grown epitaxially, thus enabling the implementation of an optoelectronic device with high efficiency and excellent reliability. Due to the increased optical extraction efficiency, it is also possible to implement a high-power LD or LED.

[0065] Meanwhile, the integrated cavity C can enable a structure in which the connections between the substrate 100 and the nitride semiconductor layer 155 are minimized. Since the substrate 100 and the nitride semiconductor layer 155 are physically separated to some extent, voltage generation is further suppressed. Thus, as the nitride semiconductor layer 155 grows and is then cooled, the nitride semiconductor layer 155 and the substrate 100 can be naturally separated from each other with only a small physical force or impact, without applying a large amount of energy such as a laser, as shown in Fig. 2(g) and Fig. 3(g) is shown.

[0066] In particular, in one embodiment, the area occupied by the cavity C is larger than the area occupied by the leg parts 130a. Although the laser detachment method is not used, the nitride semiconductor layer 155 can therefore be easily separated from the substrate 100. Since the separation is natural or occurs with only a small force, the nitride semiconductor layer 155 may not be bent, torn, or broken. Therefore, the present disclosure is very advantageous for applications where the substrate 100 and the nitride semiconductor layer 155 need to be separated, for example, in a vertical LED, a horizontal LED, or an LED that is transported to any substrate, and furthermore, the substrate 100 can be easily reused.Furthermore, if the nitride semiconductor layer 155 is formed as a thick film and is separated from the substrate 100, the nitride semiconductor layer 155 can be used as a freestanding nitride semiconductor substrate, and thus it is easy to produce a nitride semiconductor substrate as the same type of substrate for excellent nitride semiconductor growth.

[0067] As described above, in the present disclosure, the substrate 100 and the nitride semiconductor layer 155 are connected only by points instead of a line in order to minimize the connection between the nitride semiconductor layer 155 and the substrate 100. The point-connected part is the leg portion 130a of the inorganic thin film 130' and may have a hollow tube shape. To form the leg portion 130a in a tube shape, in one embodiment of the present disclosure, the hole-type sacrificial layer structuring 120 and the inorganic thin film 130 formed by ALD are used. A final structure obtained by removing the sacrificial layer structuring 120 has the continuously connected integrated cavity C.

[0068] Due to the integrated cavity C, the physical removal process can be easily carried out without the use of a laser.

[0069] Fig. Figure 7 is a diagram showing that the leg part 130a, which connects the nitride semiconductor layer 155 and the substrate 100, namely the column, has a region that is Fig. 7(a) to Fig. 7(d) gradually decreases, so that the nitride semiconductor layer 155 and the substrate 100 can be separated with a smaller force. In one embodiment of the present disclosure, the leg part 130a with a columnar structure has a hollow tube shape, as shown in Fig. 7(d) is shown, thereby minimizing a direct connection between the nitride semiconductor layer 155 and the substrate 100. In the present disclosure, the nitride semiconductor layer 155 is supported using the inorganic thin film 130', which has the leg portion 130a with a hollow tube shape as described above.

[0070] According to the present disclosure, it is possible to direct the dislocation so that it is generated only over leg part 130a, namely the hole, and although AlN grows, unlike in PSS, excellent crystal quality is ensured. Furthermore, the bending caused by a difference in the coefficient of thermal expansion can be prevented by utilizing the property of the integrated cavity C to absorb stress.

Claims

[1] Substrate structure, comprising: a single crystal substrate heterogeneous to a nitride semiconductor (100) and a crystallized inorganic thin film (130') having several leg parts (130a) configured to contact the substrate (100) such that an integrated cavity (C) is defined between the leg parts (130a) and the substrate (100), and an upper surface (130b) formed continuously so that it extends from the several leg parts (130a) and parallel to the substrate (100), wherein the crystallized inorganic thin film (130') has the same crystal structure as the substrate (100) and wherein the several leg parts (130a) each have a hollow tube shape. [2] Substrate structure according to claim 1, wherein an area occupied by the cavity (C) is larger than an area occupied by the leg parts (130a). [3] Semiconductor lamination structure, comprising: a single crystal substrate heterogeneous to a nitride semiconductor (100); a crystallized inorganic thin film (130') having several leg parts (130a) configured to contact the substrate (100) and an upper surface (130b) formed continuously and extending from the leg parts (130a) and parallel to the substrate (100), such that an integrated cavity (C) is defined between the leg parts (130a) and the substrate (100), wherein the crystallized inorganic thin film (130') has the same crystal structure as the substrate (100); and a nitride semiconductor layer (150) formed on the inorganic thin film (130'), wherein the several leg parts (130a) each have a hollow tube shape. [4] Semiconductor lamination structure according to claim 3, wherein the nitride semiconductor layer (150) grows on the crystallized inorganic thin film (130') above the integrated cavity (C) and is merged with it. [5] Methods for forming a substrate structure, comprising: Formation of a hole-type sacrificial layer structure (110) on a single crystal substrate (100) heterogeneous to a nitride semiconductor; Forming an inorganic thin film (130) on the sacrificial layer structuring (110) such that the inorganic thin film (130) has several leg parts (130a) each having a hollow tube shape and a surface (130b) that is formed continuously, so that it extends from the several leg parts (130a) and parallel to the substrate (100); Removing the sacrificial layer structure (110) from the substrate (100) on which the inorganic thin film (130) is formed, so that an integrated cavity (C) is formed which is defined by the substrate (100) and the inorganic thin film (130); and Crystallizing the inorganic thin film (130) into the same crystal structure as the substrate (100). [6] Method for forming a substrate structure according to claim 5, wherein the inorganic thin film (130) is formed by atomic layer deposition (ALD). [7] Method for forming a substrate structure according to claim 5, wherein the sacrificial layer structuring (110) is removed by heat treatment in an oxygen atmosphere or wet removal using an organic solvent. [8] Method for forming a substrate structure according to claim 7, wherein the sacrificial layer structuring (110) is removed by heat treatment in an oxygen atmosphere and the inorganic thin film (130) is crystallized by heat treatment at a high temperature. [9] Method for forming a semiconductor lamination structure, comprising: Formation of a hole-type sacrificial layer structure (110) on a single crystal substrate (100) heterogeneous to a nitride semiconductor; Forming an inorganic thin film (130) on the sacrificial layer structure (110) such that the inorganic thin film (130) has several leg parts (130a), each having a hollow tube shape, and a surface (130b) that is formed continuously, so that it extends from the several leg parts (130a) and parallel to the substrate (100), Removing the sacrificial layer structure (110) from the substrate (100) on which the inorganic thin film (130) is formed, so that an integrated cavity (C) defined by the substrate (100) and the inorganic thin film (130) is formed; Crystallization of the inorganic thin film (130) into the same crystal structure as the substrate (100) and Growth of a nitride semiconductor layer (150) on the crystallized inorganic thin film (130') over the cavity (C). [10] Method for producing a nitride semiconductor, comprising: Formation of a hole-type sacrificial layer structure (110) on a single crystal substrate (100) heterogeneous to a nitride semiconductor; Forming an inorganic thin film (130') on the sacrificial layer structuring (110) such that the inorganic thin film (130) has several leg parts (130a) each having a hollow tube shape and a surface (130b) that is formed continuously, so that it extends from the several leg parts (130a) and parallel to the substrate (100); Removing the sacrificial layer structure (110) from the substrate (100) on which the inorganic thin film (130) is formed, so that an integrated cavity (C) defined by the substrate (100) and the inorganic thin film (130) is formed; Crystallizing the inorganic thin film (130) into the same crystal structure as the substrate (100); Growth of a nitride semiconductor layer (150) on the crystallized inorganic thin film (130') over the cavity (C) and Separation of the substrate (100) and the nitride semiconductor layer (150).

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